1. Understanding Evolution in terms of Genetics

2. DARWIN’S UNDERSTANDING VS. PRESENT DAY
How are inheritable traits passed?
How do variations appear?
Today’s understanding of genes, DNA, variation, and mutations is central to our understanding of how evolution works

3. Bigger Picture MICROEVOLUTION MACROEVOLUTION
Mutations
Natural selection billion years = Macroevolution
Genetic Drift
Gene flow
Mutations & Gene shuffling
Natural selection of traits
Single gene traits
Polygenic traits
Genetic drift
Gene flow
Adaptive radiation
Convergent & divergent evolution
Coevolution
Gradualism
Punctuated equilibrium
Mass extinction
Bigger Picture
Smaller Picture

4. POPULATIONS AND GENE POOLS
Population: group of the same species that interbreed
Gene pool: consists of all genes, including all the different alleles, that are present in a population
Large gene pool
High genetic diversity
Increased chances of biological fitness & survival
Small gene pool
Low genetic diversity
Decreased chances of biological fitness & extinction

5. Microevolution – Mutations & Gene Shuffling
Not all mutations are harmful
Some mutations can actually be beneficial & increase organism’s fitness
Gene shuffling will produce different phenotypes
No change the relative frequency of alleles in the populations

6. Microevolution – Natural selection of Traits
Single Gene Traits
Polygenic traits
Controlled by a single gene that has two alleles
Variation only leads to two possible phenotypes
Represented with a bar graph
Controlled by two or more genes
Polygenic traits have many possible genotypes and phenotypes
Represented with a bell shaped or “normal distribution” curve
Ear lobe attached Ear lobe detached

7. Effect of Natural selection on Single Gene traits
Changes in allele frequencies
Evolution

8. Effect of Natural selection on polygenic traits

9. Directional selection
A single phenotype is favored
Due to environmental changes

10. Stabilizing selection
An intermediate phenotype is favored
More homogenous population

11. Disruptive selection Often extreme phenotypes are favored
Main driving force behind speciation

12. Microevolution – Genetic Drift
Genetic drift: Large changes in allele frequencies due to a random event
Small gene pool
Low genetic diversity
Decreased chances of biological fitness & extinction
FOUNDER EFFECT
BOTTLE NECK EFFECT

13. FOUNDER EFFECT
BOTTLENECK EFFCT

14. Microevolution – Gene flow

15. Speciation
Behavioral Isolation: Differences in traits or habits

16. Speciation
Geographical Isolation: Land separation of individuals

17. Speciation
Temporal Isolation: Mating season is different

18. Evolution of Darwin’s Finches1 2 3 4 5

19. Macroevolution Patterns
Adaptive radiation

20. Habitat & Niche
Habitat: It is the place where an organism lives (Where do you live?)
Niche: The niche refers to the role of the organism in the system (What do you do?)

21. Convergent Evolution
Penguin Seal
Bird Mammal
No common
ancestor

22. Divergent Evolution
Polar Bear Brown Bear
common
ancestor

23. Macroevolution Patterns
Coevolution

24. Macroevolution Patterns
Gradualism
Punctuated equilibrium

27. Macroevolution Patterns

28. Cretaceous-Tertiary mass extinction (aka- K/T extinction)
Wipe out of Dinosaurs
Triassic-Jurassic mass extinction
Many marine reptile, amphibians were lost
Permian mass extinction (aka Great Dying)
96% of species died. All life on Earth today is descended from the 4% of species that survived
Late Devonian mass extinction
Three quarters of all species on Earth died out
Ordovician-Silurian mass extinction
Lots of sea creatures were lost

31. Macroevolution Patterns
Convergent Evolution
Divergent Evolution